Editorial Anonymous provided a great explanation of basic picture book construction a few months ago.
At that time, I skimmed the info. Today, I'm studying it.
Why? An editor asked me to make page breaks on my current manuscript. And know what? I had more page breaks than a 32-page picture book would allow! Whoops. I knew that my manuscript had to fall within the 500- to 800-word length, but I had neglected to pay attention to logical page breaks.